Fastener driving apparatus



1970 0. A. WANDEL E TAL 3,46,4@

. FASTENER DRIVING APPARATUS Filed Jan. 29, 1968 2 Sheets-Sheet 1 I se Was IOO INVENTORS: OSCAR A. WANDEL THOMAS H. DORNEY Feb. 24, 197 o. A.WANDEL ET A; smwm FASTENER DRIVING' APPARATUS Filed Jan. 29, 1968 2Sheets-Sheet 2 no Q FIG. 4

INVENTORS: OSCAR A. WAN DE L United States Patent 3,496,840 FASTENERDRIVING APPARATUS Oscar A. Wandel, Mundelein, and Thomas H. Dorney, WoodDale, IlL, assignors to Fastener Corporation, Franklin Park, 111., acorporation of lllinois Filed Jan. 29, 1968, Ser. No. 701,380 Int. Cl.F01b 11/02; B25c 1/04; B25d 9/02 US. CI. 92-85 3 Claims ABSTRACT OF THEDISCLOSURE There is provided a fastener driving apparatus havingimproved means for arresting movement of the piston. The fastenerdriving apparatus is of the type having a cylinder within a housing anda piston slideably mounted in the cylinder movable through the fastenerdriving stroke toward one end of the cylinder. An annular resilientbumper forming a stop or arrester is provided to arrest movement of thepiston at the end of the cylinder. Such resilient bumper is providedwith relieved areas in the form of chamfers or openings to provideadditional flexibility in the relieved areas, avoid chipping andbreakdown, and achieve longer life by improving circulation.

This invention relates to a fastener driving apparatus, and, moreparticularly, to a fastener driving apparatus including new and improvedmeans for arresting movement of a piston.

Fastener driving tools of the type in which a fastener driving elementis moved through a power stroke by a fluid or pneumatically actuateddrive piston commonly include bumper means cushioning the termination ofthe power stroke of the drive piston. These bumpers or bumper assembliesgenerally have been formed of resilient material, such as one or morebodies of natural or synthetic rubber, disposed inthe path of movementof the drive piston adjacent the lower end of the cylinder. Althoughthese assemblies function properly throughout an operating lifecommensurate with the expected useful life of prior tools, the presentdesign of tools for driving larger fasteners, such as common nails, andfor longer life has made it necessary to obtain greater energy from thedrive piston during the power stroke. This means that greater and moreforce must be damped or absorbed from the drive piston at thetermination of the power stroke. Moreover there is an increasing use ofautomatically recycling fastener driving tools which continuously andrepetitively operate so long as the control valve or trigger ismaintained depressed. Such rapid repetitive operation of the fastenerdriving required rapid dissipation of the heat developed in the bumperto prevent excessive buildup of the operating temperature. Heretoforethe rubber or resilient body or bumper has not been entirelysatisfactory in withstanding increased forces or the greater number ofrepeated forces over extended periods of time.

Accordingly one object of the present invention is to provide a new andimproved fastener driving apparatus.

Another object of the present invention is to provide a fastener drivingapparatus including a new and improved bumper assembly.

Another object of the present invention is to provide a fastener drivingtool including new and improved means for cushioning the termination ofthe power stroke of the drive piston in the tool.

In accordance with these and other objects, there is provided a new andimproved fastener driving tool having improved means for arrestingmovement of the piston at the termination of its power stroke. Morespecifically there is provided an annular or ring shaped resilientbumper in the path of movement of the drive piston adjacent to lower endof the cylinder. In accordance with 3,496,840 Patented Feb. 24, 1970 thepresent invention the annular bumper is provided with relieved areaswhich may be in the form of tapers, grooves, longitudinal passageways,and the like. Such relieved areas contribute to longer life of thebumper by providing improved cooling elfects and permitting the workingfluid or air to circulate around and through the relief. Additionallychamfers, tapers and other reliefs avoid chipping and breakdown of thebumper at relieved points. Moreover the bumpers according to the presentinvention provide additional flexibility in the relieved areas andtherefore improved cushioning effect of the drive piston.

Many other objects and advantages of the present invention will becomeapparent from considering the following detailed description inconjunction with the drawings in which:

FIG. 1 is a fragmentary cross sectional view of a fastener driving toolincorporating the improved arrester assembly according to the presentinvention;

FIG. 2 is a plan view of a modified bumper assembly according to thepresent invention;

FIG. 3 is a cross sectional view of the bumper assembly of FIG. 2, takenalong line 33 of FIG. 2;

FIG. 4 is a plan view of yet another embodiment of a bumper assemblyaccording to the present invention;

FIG. 5 is a cross sectional view of the bumper assembly of FIG. 4, takenalong line 55 of FIG. 4;

FIG. 6 illustrates in plan view yet another embodiment of a bumperassembly according to the present invention; and

FIG. 7 is a cross sectional view of the bumper assembly of FIG. 6, takenalong line 77 of FIG. 6.

Referring now to the drawings, and particularly to the embodiment ofFIG. 1, there is illustrated a fastener driving tool generallyillustrated as 10, which embodies an improved bumper or arresteraccording to the present invention. The tool 10 may be of knownconstruction and, as illustrated, is similar to that shown and describedin the application for Letters Patent of the United States, Ser. No.602,728, filed Dec. 19, 1966, of the invention of Richard H. Doyle.However the improved bumper arrangement may be incorporated into otherfastener driving tools, such as those illustrated in Letters Patent ofthe United States No. 3,173,340 issued Mar. 16, 1965 to Richard H. Doyleand in Letters Patent of the United States No. 3,043,272 issued July 10,1962 to Oscar A. Wandel et a1. Accordingly the fastener driving tool 10is described only briefly. The tool 10 comprises a housing 12 includinga generally vertically extending head or forward portion 12a and arearwardly extending hollow handle portion 12b defining a fluidreservoir 16. Pressurized fluid such as compressed air is supplied tothe fluid reservoir of the tool by a suitable flexible line. The drivesystem for the tool 10 includes a main or power cylinder 18 mountedwithin the head portion 12a having an open upper end 18a that is adaptedto be selectively connected to the reservoir 16. The open upper end ofthe cylinder 18 is in engagement with a diaphragm type main or cylindervalve assembly 20, here shown of the poppet type, under the control of acontrol valve assembly 22 according to the present invention. A fastenerdriving assembly 24 slideably mounted within the cylinder 18 includes awork or drive piston 26 and has connected thereto a depending driverblade member 28. The fastener driving assembly 24 is normally biased toa position with the piston 26 adjacent the cylinder valve assembly 20.An exhaust valve assembly indicated generally as 32 is provided forcontrolling the selective connection at the upper end of the cylinder 18to the atmosphere.

When the tool 10 is to be operated compressed fluid from the reservoir16 enters the upper open end 18a .of the cylinder 18 and drives thefastener driving assembly 24 downwardly to engage and set a fastener ornail supplied to a drive track in a nosepiece or nosepiece structure 38.The flow of compressed fluid into the upper end of the cylinder 18 iscontrolled by the main valve assembly 20 which includes a diaphragm 40,the periphery of which is clamped between a cap 42 and the head portion12a of the housing 12 and which seats against the upper edge 18a of thecylinder 18. The diaphragm 40 is resiliently biased against the upperedge surface 18a by a spring 44 located between the cap 42 and thediaphragm 40. The cylinder side of the diaphragm 40 is continuously inconnection with the fluid reservoir 16 through a suitable passageway 46so that the pressurized fluid continuously acts against the cylinderside of the diaphragm 40 to displace the diaphragm 40 from the edge 18aof the cylinder 18. However pressurized fluid is also introduced to theopposite side of the diaphragm 40 through a passageway 48 while thefastener driving tool is in a static or at rest position. The pressureacting on the diaphragm 40 is eflective to maintain the diaphragm 40 ina closed position. If the pressurized fluid above the diaphragm 40 isdischarged, the pressurized fluid acting through the passageway 46 isthen effective to unseat the diaphragm 40 from the edge 18a of thecylinder 18 to dump pressurized fluid into the top of the main cylinder18 and to drive the piston 26 through a drive stroke.

When the fastener driving tool 10 is at rest, or during the returnstroke of the drive piston, the open upper end of the cylinder 18 isexhausted to the atmosphere through the exhaust valve assembly 32. Inthe illustrated embodiment the exhaust valve assembly comprises a hollowvalve stem 50 secured to the diaphragm connecting the upper end of thecylinder 18 to the atmosphere through a suitable exhaust passageway 52.However when the drive piston is operated through a fired or drivestroke, it is necessary for the upper end of the cylinder 18 to beclosed, and to this end there is provided a valve seat 54 disposedadjacent the end of the valve stem 50 remote from the cylinder 18 andadapted to be engaged by the valve stem 50 when the diaphragm 40 israised at the initiation of a drive stroke, thereby closing off theupper end of the cylinder 18 to the atmosphere.

To provide for the return drive of the fastener driving assembly 24,there is provided a return chamber 60 communicating with the lower endof the cylinder 18 through a plurality of ports 62. The drive piston 26is provided with suitable one way valve means 63, which may be of thetype more fully described in the above mentioned application Ser. No.602,728. Briefly the piston 26 is provided with spaced O-rings includingan upper O-ring 68 which functions as a sealing member effecting apneumatic seal between the piston 26 and the inner wall of the cylinder18, and a lower O-ring 72 expandable upon a selected pressuredifferential between the upper and lower ends of the cylinder throughthe piston 26 so as to unseat and provide for fluid to bypass the piston26 through fluid passageways 74 and around the O-ring 72 and to supplyair to the air return chamber 60.

The operation of the tool is controlled through the control or triggervalve 22. In the illustrated embodiment the control valve 22 functionsas a three way valve effective When a trigger 80 is released to connectthe cylinder valve 20 to the fluid reservoir 16 through the passageway48 and an additional passageway 82, and effective when depressed to sealoff the passageway 82 and to exhaust the cylinder valve 20 to theatmosphere through the passageway 48 and through a passageway 84 definedaround the stem 86 of a valve member 88.

To cushion or arrest the drive stroke of the piston 26, there isprovided a resilient annular bumper 90, in accordance with the presentinvention, and positioned at the lower end of the cylinder 18 which isengageable by the piston 26 as it reaches the end of its drive stroke.

It will be understood in operation of the illustrated tool 10 that solong as the trigger 80 is released, pressure from the reservoir ismaintained above the cylinder valve 40 maintaining the piston 26 in itsupper or static position. This pressure is maintained above thediaphragm 40 through the passageways 48 and 82. However upon depressionof the trigger so as to move the valve member 88 to close the passageway82, the pressure above the diaphragm 40 is exhausted through thepassageways 48 and 84. At this time a pressure below the diaphragm 40will unseat the diaphragm and dump pressurized fluid into the cylinder18 driving the piston 26 downwardly through a drive stroke. When thepiston 26 reaches the end of section is provided in the lower surface ofthe bumper 90. so as to arrest its downward movement. Moreover as soonas the piston 26 engages the bumper 90, an exhaust 92 defined betweenthe driver blade 28 and a washer member 94 is sealed from communicationwith the lower end of the cylinder 18, and the pressure buildupoccurring above the piston 26 will be effective to unseat the O-ring 72thus creating a pressure buildup in the return air chamber 60. As soonas the trigger 80 is released, so as to close the cylinder valve 20, thepressurized fluid in the air return chamber 60 will return the piston 26back to its static or normal position.

Referring now to the annular resilient bumper defining a stop orarrester for the piston 26, the bumper 90 is generally ring shaped withan inner or central opening 96 through which the driver blade 28 passes.Moreover the outer surface 98 of the bumper 90 is contained within asuitable circular recess 100 in the housing 12. The inner centralopening 96 is relieved by the provision of a tapered central openingportion 96a extending upwardly toward the piston. Additionally the upperouter corners are chamfered, as at 102 to provide the necessary reliefand to provide engagement with a shoulder 18b on the cylinder 18 toretain the bumper 90 in place. The lower or outer corners of the bumper90 are relieved by a semicircular grooved outer edge portion 104 and anannular or ring shaped groove 106 of semicircular cross section isprovided in the lower surface of the bumper 90.

Thus the bumper 90 is provided with a configuration which considerablycontributes to the life of the bumper. Additionally the bumper 90 issubstantially more flexible in the relieved areas providing improvedcushioning for the piston 26. The chamfers and relieved edge portionsavoid chipping and breakdown at the respective points. Moreover therelieving of the bumper in the particular areas contributes to longerlife by providing improved cooling effects and permitting better aircirculation around the bumper.

FIGS. 2 and 3 illustrate another embodiment of a bumper 110 according tothe present invention. As therein illustrated there is provided thebumper 110 of generally ring shape having a central opening 112 forminga passageway for the blade 28 of a fastener driving tool 10. The upperend of the opening 112 is chamfered upwardly and outwardly as indicatedat 113. An additional chamfer along the upper and outer edge 114 isprovided, and a further chamfer 115 of greater taper than the surface113 may extend outwardly from the upper end of the taper 113. Aplurality of passages 116 extend longitudinally of the bumper 110, andspecifically comprise through apertures in the body of the bumper 110.It has been found that such longitudinally extending passages greatlycontribute to the circulation of air and the cooling of the bumper 110thus contributing to the life of the bumper.

Although the embodiment of FIG. 1 illustrates a tool having a lowerpressure chamber so that the lower end of the bumper is restricted, thebumpers according to the present invention may also be used withfastener driving tools having a vented lower cylinder end and in suchinstance the ventilation passages 116 can be vented to the atmosphere ifdesired to provide further circulation of air.

FIGS. 4 and 5 illustrate yet another embodiment of a bumper 120according to the present invention wherein the bumper 120 is providedwith a central opening 122 for the passage of a blade, having anupwardly and outwardly extending taper 123 as well as a lower enlargedflare 124, FIG. 5. The lower outer edge of the bumper 120 is grooved, asillustrated at 126. In accordance with the embodiment of FIGS. 4 and 5,there is provided a plurality of longitudinally extending passageways inthe form of flutes 128 defined in the outer surface of the bumper.

The bumper illustrated in the embodiments of FIGS. 6 and 7 is generallysimilar to that of FIGS. 4 and 5, and includes the bumper member 120 ofgenerally resilient material, having the central opening 122, thetapered portion 123, the forward portion 124, the grooved portion 126,and the flutes 128. Additionally however the bumper 130 includes aspider shaped washer 132 having a plurality of radially extending arms134 each terminating in a semicircular outer grooved edge 136 alignedwith one of the flutes 128 to provide the desired ventilation andcushioning of the bumper 130.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. In a fastener driving tool of the type having a cylinder meansdefined within a housing means and a piston slideably mounted in thecylinder means with a fastener driving blade extending from one end ofthe piston, the piston and fastener driving blade assembly being movablethrough a fastener driving stroke toward one end of said cylinder means,the improvement comprising an annular resilient bumper forming a stopfor said piston at said one end positioned within and engaging acircular recess defined at least partially in one of said means andhaving a central opening tapering outwardly at its inner end throughwhich the driving blade is adapted to move, said bumper being providedwith a plurailty of circumferential- 6 1y spaced apart longitudinalsemi-circular flutes in its outer surface.

2. A fastener driving tool as set forth in claim 1 wherein said centralopening has a lower enlarged flare extending outwardly away from thepiston.

3. A fastener driving tool as set forth in claim 1 wherein the lowerouter edge of said bumper is relieved.

References Cited UNITED STATES PATENTS 537,357 471895 Phillips 92851,481,643 1/1924 Jimerson 173139 2,699,756 1/1955 Miller 92--852,914,032 11/1959 Powers et a1 173139 X 3,104,395 9/1963 Grey et al 9285X 3,301,335 1/1967 Snelling. 3,301,456 1/1967 Schafroth et al. 227130 X3,315,951 4/ 1967 Boschi et a1. 3,320,860 5/1967 Bade 227-130 X3,396,636 8/1968 Bade 92-85 X 3,403,600 10/1968 Bade 9285 X FOREIGNPATENTS 666,302 5/ 1929 France.

1,435,655 3/1966 France.

MARTIN P. SCHWADRON, Primary Examiner IRWIN C. COHEN, Assistant ExaminerUS. or. X.R. 173-139; 227-130; 267-1

